PAR1 Is a Candidate Target for the Treatment of Peritoneal Dissemination in Gastric Cancer

Background/Aim: Peritoneal dissemination (PD) is a frequent cause of death in gastric cancer (GC), and there is evidence of an association between protease-activated receptor- 1 (PAR1) and the development of PD. This study hypothesized that PD in GC might be influenced by PAR1. Materials and Methods: The cytotoxic effect of paclitaxel (PTX) on PAR1transfected MKN45 (MKN45/PAR1) cells was analyzed using the MTT assay, and IC50 values were determined. In female athymic nude mice, MKN45/PAR1 cells were suspended in 0.05 ml phosphate-buffered saline (PBS) medium and inoculated into the stomach mid-wall. In each group, intraperitoneal injections of PBS, PTX, SCH79797 (PAR1-antagonist), or PTX plus SCH79797 were administered on days 8, 15, and 22 following tumor inoculation. At 56 days after tumor inoculation, mice were examined for both abdominal tumor nodule status and size and weight of the tumors. Results: The IC50 of PTX for MKN45/PAR1 cells was 0.0697 mu M and that of SCH79797 was 0.0145 mu M. Mean survival of the MKN45/PAR1 mice in the PBS group was 28.75 days, whereas survival times for the mice treated with SCH79797, PTX, or a combination of PTX and SCH79797 were 31.2, 49.2, and 48.5 days, respectively. Tumor weight was smaller in the group receiving PTX and SCH79797 intraperitoneally compared with that in the PBS group (1,086 +/- 127.2 mg vs. 33.2 +/- 19.9 mg; p<0.001). Conclusion: The PAR1 antagonist was found to inhibit PD in a PAR1-expressing GC cell line. PAR1 may serve as a promising therapeutic target for managing PD in gastric cancer, as it plays a crucial role in its progression.